Antitüroglobuliin

Antitüroglobuliin, also known as anti-thyroglobulin antibodies (anti-Tg), are autoantibodies directed against thyroglobulin, a large glycoprotein produced by the thyroid gland and a precursor in the synthesis of thyroid hormones T3 and T4. Thyroglobulin is released into the bloodstream in small amounts, and anti-Tg can bind to it, potentially affecting laboratory measurements.

These antibodies are commonly detected in autoimmune thyroid diseases, most notably Hashimoto's thyroiditis, and are found at lower frequencies in other thyroid conditions such as Graves’ disease. They can also be present in healthy individuals without thyroid disease, particularly at low titers. The presence and level of anti-Tg vary with age, population, and assay method, and they are not by themselves diagnostic of a specific thyroid disorder.

In clinical practice, anti-Tg testing contributes to the assessment of autoimmune thyroid disease and can be monitored over time to help gauge disease activity. In patients with differentiated thyroid cancer who have undergone thyroidectomy, anti-Tg can interfere with thyroglobulin immunoassays, potentially producing falsely high or falsely low results. When anti-Tg is present, thyroglobulin measurements may be unreliable, and physicians may rely on alternative assays or monitor anti-Tg titers or use imaging and clinical assessment for follow-up.

Measurement of anti-Tg is typically performed by immunoassays, with results reported in international units per milliliter (IU/mL). Reference ranges are assay-specific, and positivity thresholds vary. Interpreting anti-Tg requires consideration of the overall clinical context and coexisting thyroid test results.